Filters are commonly used in connection with lubrication systems and fuel systems for internal combustion engines and hydraulic systems for heavy duty equipment. Filters are also used in many other types of liquid systems. In these types of systems, the filter is changed periodically. One type of typical filter system used is a spin-on canister filter.
Spin-on canister filters are disposable units, which typically include a single-use housing holding a permanently mounted, non-replaceable filter element (cartridge filter). The canister holding the cartridge filter is usually spun onto a filter head by a threaded engagement. The liquid to be cleaned passes from the filter head and into the housing for filtering. The cleaned liquid exits the housing and reenters the filter head. After some period of use, the spin-on canister filter is removed from the filter head and is discarded. A new spin-on canister filter is then mounted onto the filter head.
Typically, there is some type of seal arrangement between the filter and the filter head. In the past, the seal arrangement could put a drag when installing and removing, which causes difficulty in maintenance. Further, in prior art designs, it takes several revolutions of the housing onto the filter head before the threads bottom out. This can cause difficulty with cross-threading or not properly mounting the filter onto the filter head. Improvements are desirable.